1. Field of the Invention
The present invention relates to a semiconductor device and a driving method of a semiconductor device. In addition, the present invention relates to a display device having a semiconductor device, in particular, relates to a liquid crystal display device having a semiconductor device and an electronic apparatus having the liquid crystal display device.
2. Description of the Related Art
In recent years, display devices such as a liquid crystal display device and a light-emitting device have been actively developed in accordance with increase in large display devices such as liquid crystal televisions. In particular, a technique in which a pixel circuit and a driver circuit including a shift register circuit or the like (hereinafter referred to as an internal circuit) are formed over the same substrate by using transistors formed of a noncrystalline semiconductor over an insulator, which contributes largely to reduction in power consumption and cost, has been actively developed. The internal circuit formed over the insulator is connected via an FPC or the like to a controller IC or the like (hereinafter referred to as an external circuit) disposed outside the insulator, and an operation thereof is controlled.
As the internal circuit formed over the insulator, various level shifters have been invented (see Reference 1: Japanese Published Patent Application No. 2001-257581, and Reference 2: Japanese Published Patent Application No. 2002-118458)